MIL-53(Al)@HC nanohybrid for bicomponent adsorption of ibuprofen and metsulfuron-methyl: Application of macro- and microscopic models and competition between contaminants

In this work, a hybrid was synthesized by hydrothermal treatment, metal-organic framework functionalized with hydrochar (MIL-53(Al)@HC) for the adsorption of two organic molecules Ibuprofen sodium salt and Metsulfuron-methyl, in binary system. The hybrid is composed of 71 wt% biomass and 29 wt% MOF. TGA, BET, FTIR, XRD and XPS characterization techniques were used to verify the hybridization of MIL-53(Al)@HC. The MIL-53(Al)@HC hybrid showed in situ MIL-53(Al) crystal growth capability. Batch adsorption experiments were carried out to study the effect of pH, adsorbent dosage, adsorbate concentration, contact time and temperature effect. The results obtained under extreme conditions demonstrate that MIL-53(Al)@HC is an adsorbent capable of removing >98% of IBU and MTM in mixture at a concentration of 0.3 mM (68 ppm IBU and 115 ppm MTM). The pseudo-second order model adequately described the adsorption kinetics and equilibrium using the Sips and Freundlich models. The physico-statistical microscopic model (2-layer) corroborated the hypothesis of a multilayer adsorption proposed by the macroscopic Freundlich model. In the competition study between IBU and MTM, both antagonistic and synergistic effects were observed. In the thermodynamic study, positive values of (ΔH°) indicate that adsorption is endothermic in nature and that the dominant mechanism is physisorption. A mechanism of adsorption by hydrogen bridging and non-covalent π*-π adsorbate-adsorbate and adsorbate-adsorbate-adsorbate interactions was proposed. The desorption study shows that in 5 washing cycles MIL-53(Al)@HC is a recoverable material.

The Role of Surface Complexes in Ketene Formation from Fatty Acids via Pyrolysis over Silica: from Platform Molecules to Waste Biomass

Fatty acids (FA) are the main constituents of lipids and oil crop waste, considered to be a promising 2G biomass that can be converted into ketenes via catalytic pyrolysis. Ketenes are appraised as promising synthons for the pharmaceutical, polymer, and chemical industries. Progress in the thermal conversion of short- and long-chain fatty acids into ketenes requires a deep understanding of their interaction mechanisms with the nanoscale oxide catalysts. In this work, the interactions of fatty acids with silica are investigated using a wide range of experimental and computational techniques (TPD MS, DFT, FTIR, in situ IR, equilibrium adsorption, and thermogravimetry). The adsorption isotherms of linear and branched fatty acids C1-C6 on the silica surface from aqueous solution have been obtained. The relative quantities of different types of surface complexes, as well as kinetic parameters of their decomposition, were calculated. The formation of surface complexes with a coordination bond between the carbonyl oxygens and silicon atoms in the surface-active center, which becomes pentacoordinate, was confirmed by DFT calculations, in good agreement with the IR feature at ∼1680 cm 1. Interestingly, ketenes release relate to these complexes' decomposition as confirmed by the thermal evolution of the absorption band (1680 cm-1) synchronously with the TPD peak of the ketene molecular ion. The established regularities of the ketenezation are also observed for the silica-induced pyrolysis of glyceryl trimyristate and real waste, rapeseed meals.

Understanding Bridging Sites and Accelerating Quantum Efficiency for Photocatalytic CO2 Reduction

We report a novel double-shelled nanoboxes photocatalyst architecture with tailored interfaces that accelerate quantum efficiency for photocatalytic CO2 reduction reaction (CO2RR) via Mo-S bridging bonds sites in Sv-In2S3@2H-MoTe2. The X-ray absorption near-edge structure shows that the formation of Sv-In2S3@2H-MoTe2 adjusts the coordination environment via interface engineering and forms Mo-S polarized sites at the interface. The interfacial dynamics and catalytic behavior are clearly revealed by ultrafast femtosecond transient absorption, time-resolved, and in situ diffuse reflectance-Infrared Fourier transform spectroscopy. A tunable electronic structure through steric interaction of Mo-S bridging bonds induces a 1.7-fold enhancement in Sv-In2S3@2H-MoTe2(5) photogenerated carrier concentration relative to pristine Sv-In2S3. Benefiting from lower carrier transport activation energy, an internal quantum efficiency of 94.01% at 380 nm was used for photocatalytic CO2RR. This study proposes a new strategy to design photocatalyst through bridging sites to adjust the selectivity of photocatalytic CO2RR.

Heterogeneous Catalysis to Drive the Waste-to-Pharma Concept: From Furanics to Active Pharmaceutical Ingredients

A perspective on the use of heterogeneous catalysis to drive the waste-to-pharma concept is provided in this contribution based on the conversion of furanics to active pharmaceutical ingredients (APIs). The provided overview of the concept in this perspective article has been exemplified for two key molecule examples: Ancarolol and Furosemide.

Mechanochemical Preparation of Magnetically Separable Fe and Cu-Based Bimetallic Nanocatalysts for Vanillin Production

A highly sustainable method for the preparation of supported iron oxide and copper nanoparticles (NPs) on a biomass-derived carbon by solvent-free mechanochemical process is reported. In-situ mechanochemically obtained extracts from orange peel could behave as a green reducing agent, allowing the formation of Cu metal nanoparticles as well as generating a magnetic phase (magnetite) in the systems via partial Fe3+ reduction. At the same time, orange peel residues also served as template and carbon source, adding oxygen functionalities, which were found to benefit the catalytic performance of mechanochemically synthesized nanomaterials. The series of magnetic Cu-Fe@OP were tested in the oxidation of trans-ferulic acid towards vanillin, remarkably revealing a maximum vanillin yield of 82% for the sample treated at 200 °C.

Metal doping of porous materials via a post-synthetic mechano-chemical approach: a general route to design low-loaded versatile catalytic systems

Mesoporous silica materials doped with metals (Fe/Zr) presented superior catalytic performance for oxidations. The use of MOFs as metal sources improved the metal distribution, and allowed a fine-tuning of Brønsted–Lewis acidity depending on the MOF.

Sustainable and recyclable heterogenous palladium catalysts from rice husk-derived biosilicates for Suzuki-Miyaura cross-couplings, aerobic oxidations and stereoselective cascade carbocyclizations

A new eco-friendly approach for the preparation of sustainable heterogeneous palladium catalysts from rice husk-derived biogenic silica (RHP-Si and RHU-Si). The designed heterogeneously supported palladium species (RHP-Si-NH2-Pd and RHU-Si-NH2-Pd) were fully characterized and successfully employed as catalysts for various chemical transformations (C-C bond-forming reactions, aerobic oxidations and carbocyclizations). Suzuki-Miyaura transformations were highly efficient in a green solvent system (H2O:EtOH (1:1) with excellent recyclability, providing the cross-coupling products with a wide range of functionalities in high isolated yields (up to 99%). Palladium species (Pd(0)-nanoparticles or Pd(II)) were also efficient catalysts in the green aerobic oxidation of an allylic alcohol and a co-catalytic stereoselective cascade carbocyclization transformation. In the latter case, a quaternary stereocenter was formed with excellent stereoselectivity (up to 27:1 dr).

Tuneable Acidity in Fluorinated Al-SBA-15 Materials for the Esterification of Valeric Acid to Alkyl Valerates

The acidity of Al-SBA-15 materials functionalized by ball milling with several niobium loadings (0. 25-1 wt.%) as well as with several fluorine loadings (by wet impregnation using NH₄F as a precursor) was characterized and materials investigated in the esterification of valeric acid to alkyl valerates. The parent Al-SBA-15 support as well as the modified materials loaded with Nb and/or F have been catalysts synthesized characterized by X-ray diffraction (XRD), N₂ physisorption measurements, and diffuse reflection infrared spectroscopy (DRIFT) among others. A special interest was paid on the acidity of the materials that was investigated by temperature-programmed desorption of pyridine. Interestingly, the characterization results for the materials containing fluorine showed up an increase in the acidity strength despite of a reduction in the number of acid sites. The catalytic performance of the as-prepared catalysts was investigated in the microwave-assisted esterification reaction of valeric acid to valerate esters. Thus, while the materials modified with niobium exhibited a lower catalytic activity as compared with the catalytic support (Al-SBA-15), the materials loaded with fluorine either onto Al-SBA-15 or on Nb1%/Al-SBA-15 materials presented enhanced conversion values of valeric acid. Therefore, it can be said that the new acid sites with enhanced strength formed by the incorporation of fluorine boost the esterification of valeric acid with alcohols to form the respective valerate ester.

One-Pot Cu/TiO2 Nanoparticles Synthesis for Trans-Ferulic Acid Conversion into Vanillin

In this study, the co-synthesis of TiO₂ and Cu metallic nanoparticles obtained via one-pot cost-efficient hydrothermal process has been addressed. Different nanocatalysts with Cu contents were characterized by X-ray diffraction, nitrogen porosimetry, scanning electron microscopy, and transmission electron microscopy. The TiO₂ and Cu metallic nanoparticles were synthesized with copper loading up to one (Cu/Ti atomic ratio). Synthesized catalysts exhibited pore sizes in the mesoporous range and high surface areas above 150 m²/g. The particle size for TiO₂ presented a homogeneous distribution of approximately 8 nm, moreover, Cu nanoparticles varied from 12 to >100 nm depending on the metal loading. The nanostructured materials were successfully tested in the conversion of trans-ferulic acid into vanillin under sustainable conditions, achieving the best performance for 0.3 Cu/Ti atomic ratio (70% vanillin yield).

Effect of Bay Leaves Essential Oil Concentration on the Properties of Biodegradable Carboxymethyl Cellulose-Based Edible Films

Films containing bay leaves essential oils (BEOs) were prepared and evaluated for edible packaging applications. The BEOs were extracted by the Soxhlet method, using ethanol or methanol as organic solvent. Then, films were prepared by “solvent casting” technique using carboxymethyl cellulose (CMC), with different concentrations for the as-obtained BEOs (from 1% to 30% wt.). The resulting films were characterized to evaluate their physical (thickness, moisture content, water solubility and water vapor permeability), optical (transparency and UV-light barrier), mechanical (tensile strength and elongation at break), antioxidant and antimicrobiological properties Attractive films were obtained for food active packaging applications, as they presented a high antioxidant activity (up to 99%) and total phenolic content, and good barrier properties against water vapor (50% improved of CMC) in the case of CMC-film containing 15% wt. ethanolic extract. Related to optical properties, UV-light barrier effect was increased (almost 100% of protection) avoiding typical lipids oxidation in food systems. High water solubility (93%) was also found, ensuring also their biodegradability. Moreover, it was demonstrated that developed films inhibit microorganisms’ growth (Escherichia coli and Candida glabrata), this avoiding an early food oxidation.

Continuous Flow Synthesis of High Valuable N-Heterocycles via Catalytic Conversion of Levulinic Acid

Graphitic carbon nitride (g-C₃N₄) was successfully functionalized with a low platinum loading to give rise to an effective and stable catalytic material. The synthesized g-C₃N₄/Pt was fully characterized by XRD, N₂ physisorption, XPS, SEM-Mapping, and TEM techniques. Remarkably, XPS analysis revealed that Pt was in a dominant metallic state. In addition, XPS together with XRD and N₂ physisorption measurements indicated that the g-C₃N₄ preserves its native structure after the platinum deposition process. g-C₃N₄/Pt was applied to the catalytic conversion of levulinic acid to N-heterocycles under continuous flow conditions. Reaction parameters (temperature, pressure, and concentration of levulinic acid) were studied using 3 levels for each parameter, and the best conditions were employed for the analysis of the catalyst's stability. The catalytic system displayed high selectivity to 1-ethyl-5-methylpyrrolidin-2-one and outstanding stability after 3 h of reaction.

Sol-Gel Immobilisation of Lipases: Towards Active and Stable Biocatalysts for the Esterification of Valeric Acid

Alkyl esters are high added value products useful in a wide range of industrial sectors. A methodology based on a simple sol-gel approach (biosilicification) is herein proposed to encapsulate enzymes in order to design highly active and stable biocatalysts. Their performance was assessed through the optimization of valeric acid esterification evaluating the effect of different parameters (biocatalyst load, presence of water, reaction temperature and stirring rate) in different alcoholic media, and comparing two different methodologies: conventional heating and microwave irradiation. Ethyl valerate yields were in the 80–85% range under optimum conditions (15 min, 12% m/v biocatalyst, molar ratio 1:2 of valeric acid to alcohol). Comparatively, the biocatalysts were slightly deactivated under microwave irradiation due to enzyme denaturalisation. Biocatalyst reuse was attempted to prove that good reusability of these sol-gel immobilised enzymes could be achieved under conventional heating.

Vapor-Phase Hydrogenation of Levulinic Acid to γ-Valerolactone Over Bi-Functional Ni/HZSM-5 Catalyst

The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in vapor-phase is economically more viable route if compared to reaction in liquid-phase. To improve the GVL yield in the vapor-phase reaction, the optimization of nickel modified zeolite as bi-functional catalyst (Ni/HZSM-5) was studied. Ni/HZSM-5 materials with fixed Al/Si molar ratio of 0.04 and different nominal Ni/Si molar ratios (from 0.01 to 0.05) were synthesized without the use of organic template and with the most affordable sources of silica and alumina. Materials were characterized by X-ray powder diffraction, SEM-EDX, TEM-EDX, pyridine TPD and DRIFTS, H₂-TPR, N₂ physisorption and isoelectric point. In the synthesized materials, 61–83% of nickel is present as bulk NiO and increases with nickel content. Additionally, in all catalysts, a small fraction of Ni²⁺ which strongly interacts with the zeolite support was detected (10–18%), as well as Ni²⁺ acting as charge compensating cations for Brønsted acid sites (7–21%). Increasing the nickel content in the catalysts leads to a progressive decrease of Brønsted acid sites (BAS) and concomitant increase of Lewis acid sites (LAS). When BAS/LAS is approaching to 1 and at the same time the amount of NiO reducible active sites is around 80%, the bi-functional Ni/HZSM-5-3 catalyst (Ni/Al = 0.59) leads to 99% conversion of LA and 100% selectivity to GVL at 320°C. This catalyst also shows stable levulinic acid hydrogenation to GVL in 3 reaction cycles conducted at 320°C. The concerted action of the following active sites in the catalyst is a key element for its optimized performance: (1) Ni metallic active sites with hydrogenation effect, (2) Lewis acid sites with dehydration effect, and (3) nickel aluminate sites with synergetic and stabilizing effects of all active sites in the catalyst.

Ultrasound-Assisted Esterification of Valeric Acid to Alkyl Valerates Promoted by Biosilicified Lipases

A novel, environmentally friendly, and sustainable ultrasound-assisted methodology in the valorization of valeric acid to alkyl valerate using a biosilicified lipase from Candida antarctica is reported. This one-pot room temperature methodology of enzyme biosilicification leads to biosilicified lipases with improved activity and reaction efficiency as compared to free enzymes. Yields in the ultrasound-promoted esterification of valeric acid was ca. 90% in 2 h with 15% m/v of biosilicified lipase (Bio-lipase; 616 U/g _biocatalyst enzymatic activity) and a molar ratio 1:2 (valeric acid:ethanol), slightly superior to that observed by the free enzyme (75% conversion, 583U/g _biocatalyst enzymatic activity). The reuse of enzymes in these conditions was tested and the results show a relatively good reusability of these biosilicified enzymes under the investigated conditions, particularly preserving fairly stable specific activities (616 vs. 430 U/g _biocatalyst after four reuses).

Solventless mechanochemical preparation of novel magnetic bioconjugates

A solventless mechanochemical approach was employed to obtain a bioconjugate (BSA-DA-Fe₂O₃) based on bovine serum albumin (BSA) and dopamine (DA) coated iron oxide magnetic nanoparticles. UV-vis measurements of the obtained material showed a distinctive peak at 280 nm which, together with the presence of N on the surface of the nanomaterial (a band at 400 eV in the XPS spectrum) and zeta potential measurements, confirmed the successful immobilization of the protein. Additionally, the presence of two bands at 1652 and 1545 cm^-1 in the FT-IR spectra of both BSA and BSA-DA-Fe₂O₃ and steady-state fluorescence analysis validated that the protein preserved its native-like structure after the mechanochemical milling process. Also the functionalized MNPs preserved their magnetic properties as have been demonstrated by their magnetic susceptibility value.

Highly efficient direct oxygen electro-reduction by partially unfolded laccases immobilized on waste-derived magnetically separable nanoparticles

A biocatalytic system based on laccase functionalized waste-derived iron oxide nanoparticles (LAC-DA-Fe₂O₃) was designed by a mechanochemical approach and employed in the electrocatalytic reduction of oxygen. Full characterization of the obtained bioconjugates revealed that the protein adopted a partially unfolded state. The mentioned configuration, together with the geometry coordination changes along the T1 center can be further related to a high bioelectrocatalytic response. A current density up to 2.9 mA cm^-2 has been achieved, which is among the highest values reported in literature for laccase functionalized nanomaterials.

A comprehensive study on the continuous flow synthesis of supported iron oxide nanoparticles on porous silicates and their catalytic applications

The present work demonstrates an efficient continuous flow methodology for the preparation of iron oxide nanoparticles supported on porous silicates.

Wheat bran valorisation: Towards photocatalytic nanomaterials for benzyl alcohol photo-oxidation

In this work, we have successfully synthesized a set of titania photocatalytic nanocomposites by the incorporation of different TiO₂ content on wheat bran residues. The obtained catalysts were characterized by different techniques including UV-Vis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM) while their photocatalytic activity was investigated in the oxidation of benzyl alcohol under UV light irradiation. Benzaldehyde yields were ca. 20%, with conversion in the systems of ca. 33% of benzyl alcohol by using 10%Ti-Bran catalyst, as compared to 33% yield to the target product (quantitative conversion of benzyl alcohol) using commercial pure TiO₂ (P-25). The photocatalytic activity results indicate that designed waste-derived nanomaterials with low TiO₂ content can efficiently photocatalyze the conversion of benzyl alcohol with relative high selectivity towards benzaldehyde.

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

Polysaccharides from natural sources and iron precursors were applied to develop new bio-nanocomposites by mechanochemical milling processes. The proposed methodology was demonstrated to be advantageous in comparison with other protocols for the synthesis of iron oxide based nanostructures. Additionally, mechanochemistry has enormous potential from an environmental point-of-view since it is able to reduce solvent issues in chemical syntheses. The catalytic activity of the obtained nanocatalysts was investigated in both the oxidation of benzyl alcohol to benzaldehyde and in the alkylation of toluene with benzyl chloride. The microwave-assisted oxidation of benzyl alcohol reached 45% conversion after 10 min. The conversion of the alkylation of toluene in both microwave-assisted and conventional heating methods was higher than 99% after 3 min and 30 min, respectively. The transformation of benzyl alcohol and toluene into valuable product in both the oxidation and alkylation reaction reveals a potential method for the valorization of lignocellulosic biomass.

Mechanochemical synthesis of graphene oxide-supported transition metal catalysts for the oxidation of isoeugenol to vanillin

Vanillin is one of the most commonly used natural products, which can also be produced from lignin-derived feedstocks. The chemical synthesis of vanillin is well-established in large-scale production from petrochemical-based starting materials. To overcome this problem, lignin-derived monomers (such as eugenol, isoeugenol, ferulic acid etc.) have been effectively used in the past few years. However, selective and efficient production of vanillin from these feedstocks still remains an issue to replace the existing process. In this work, new transition metal-based catalysts were proposed to investigate their efficiency in vanillin production. Reduced graphene oxide supported Fe and Co catalysts showed high conversion of isoeugenol under mild reaction conditions using H₂O₂ as oxidizing agent. Fe catalysts were more selective as compared to Co catalysts, providing a 63% vanillin selectivity at 61% conversion in 2 h. The mechanochemical process was demonstrated as an effective approach to prepare supported metal catalysts that exhibited high activity for the production of vanillin from isoeugenol.

Mechanochemically synthesized Ag-based nanohybrids with unprecedented low toxicity in biomedical applications

A simple and innovative mechanochemical approach was employed to synthesize Ag-polysaccharide nanohybrid materials that were proved to exhibit remarkable surface properties and structures for biomedical applications. The synthesized Ag nanomaterials possessed an unprecedented low cytotoxicity against human cell lines A549 and SH-SY5Y as compared to similarly reported Ag nanomaterials due to the stability and low release of Ag⁺ and high biocompatibility of the nanohybrids.

Towards the photophysical studies of humin by-products

Photophysical studies on humins and separated humin fractions were carried out using steady-state and time-resolve fluorescence techniques.

Insights into the activity, selectivity and stability of heterogeneous catalysts in the continuous flow hydroconversion of furfural

The continuous flow hydroconversion of furfural to a range of furanic derivatives was carried out using a range of metal-containing heterogeneous catalysts in order to provide insights into the reaction pathways for the hydrogenation of furfural.

Mechanochemical preparation of advanced catalytically active bifunctional Pd-containing nanomaterials for aqueous phase hydrogenation

The preparation of supported Pd nanoparticles on porous materials was successfully achieved using a simple, fast and efficient reactive milling (mechanochemical) method. The catalytic activity of different Pd/Al-SBA-15 and Pd/Al-MCF materials was investigated in the hydrogenation of p-nitrophenol (PNP) to p-aminophenol (PAP) using NaBH₄ as a reducing agent.

Mechanochemical synthesis of advanced nanomaterials for catalytic applications

Mechanochemical synthesis emerged as the most advantageous, environmentally sound alternative to traditional routes for nanomaterials preparation with outstanding properties for advanced applications.

Simple Preparation of Novel Metal-Containing Mesoporous Starches

Metal-containing mesoporous starches have been synthesized using a simple and efficient microwave-assisted methodology followed by metal impregnation in the porous gel network. Final materials exhibited surface areas >60 m² g-1, being essentially mesoporous with pore sizes in the 10-15 nm range with some developed inter-particular mesoporosity. These materials characterized by several techniques including XRD, SEM, TG/DTA and DRIFTs may find promising catalytic applications due to the presence of (hydr)oxides in their composition.

From Waste to Healing Biopolymers: Biomedical Applications of Bio-Collagenic Materials Extracted from Industrial Leather Residues in Wound Healing

The biomedical properties of a porous bio-collagenic polymer extracted from leather industrial waste residues have been investigated in wound healing and tissue regeneration in induced wounds in rats. Application of the pure undiluted bio-collagen to induced wounds in rats dramatically improved its healing after 7 days in terms of collagen production and wound filling as well as in the migration and differentiation of keratinocytes. The formulation tested was found to be three times more effective than the commercial reference product Catrix^® (Heal Progress (HP): 8 ± 1.55 vs. 2.33 ± 0.52, p < 0.001; Formation of Collagen (FC): 7.5 ± 1.05 vs. 2.17 ± 0.75, p < 0.001; Regeneration of Epidermis (RE): 13.33 ± 5.11 vs. 5 ± 5.48, p < 0.05).